1. Field of the Invention
The present invention is directed to an improvement in the process of dyeing synthetic and natural fibrous materials.
2. Description of the Prior Art
In the dyeing of synthetic and natural fibrous materials, one of the fundamental processes involves contacting the fibrous material in a tank or vat with a dye liquor heated to an elevated temperature usually up to the boiling point of the dye liquor. When the dyeing is complete the spent dye liquor is removed from the tanks or vats and sewered. The tanks or vats are usually again filled with a fresh supply of clear warm water to start a rinse which is also sewered. Multiple rinses with warm water are quite common, continuing for as long as desired, and capped off by a final rinse with cold water. As the rinses continue, the rinse waters contain progressively smaller amounts of dye material.
In addition to the dye substance contained in the dye liquors employed, the dye liquors frequently contain a variety of chemicals depending on the particular dyeing operation employed, the dye utilized and the fibrous material being dyed. The following represent an example of chemicals which are commonly utilized in dyeing processes: acetic acid, formic acid, sodium sulfite, anionic detergent, cationic detergent, ammonium sulfate, monosodium phosphate, disodium phosphate, trisodium phosphate, sodium hexametaphosphate, soda ash, sodium chloride, etc. The pollution and environmental problems caused by the sewering of these dyes and the chemicals contained in their liquors is self-evident and needs no further elaboration.
Other disadvantages in conventional dyeing processes involve the economic losses incurred by the water from the spent dye medium and subsequent rinses which cannot be used and must be disposed.